Low-pressure tire signal



March 23, 1948. H. G. RE NNER' LOW-PRESSURE TIRE SIGNAL Filed May is,1944 Ihwcntor [fare/c1 Runner Patented Mar. 23, 1948 UNITED STATESPATENT OFFICE LOW-PRESSURE TIRE SIGNAL Harold G. Renner, Detroit, Mich.

Application May 15, 1944, Serial No. 535,679

22 Claims.

This invention relates to low pressure indicators for tires andparticularly indicators carried by the valve stems of tires.

An object of the invention is to dispose a low pressure indicator withinthe valve stem of a tire and to form at least a portion of the stem oftransparent material so that indications may be observed.

Another object is to form a tubular portion of a valve stem oftransparent material to permit observation of a low pressure indicatordisposed within the stem, and to further utilize such portion as amounting for the valve.

A further object is to dispose within a tire valve stem an expansiblechamber confining air at a pressure normally balanced by that within thestem, a predetermined expansion of such chamber being induced when thetire pressure drops predeterminedly and such expansion being used toactuate a signal. A further object is to provide said expansible chamberwith an air admission passage and to control such passage by a valvealso controlling air delivery to the tire.

A further object is to locate within a valve stem a normally hidden lowpressure signal element, to provide the stem with a transparent windowportion, and to adapt the signal element to be moved into registrationwith or be otherwise exposed through the window upon a predetermineddrop of tire pressure.

Ihese and various other objects are attained by the constructionhereinafter described and illustrated in the accompanying drawing,wherein:

Fig. l is an axial sectional view of a valve stem equipped with the lowpressure indicator showing the latter as positioned when tire pressureis normal.

Fig. 2 is a similar view showing a low pressure indicating position ofthe indicator.

Fig. 3 is an exterior view of the stem with the indicator signaling lowpressure.

li'g. 4 is a view of a slightly modified indicator um In these views,the reference character I designates a pneumatic tire equipped with atubular valve stem 2, it being preferred to form the main body of suchstem of rubber as is common. A tube 3 of transparent material such as asuitable plastic forms the outer end portion of the stem, beingvulcanized or cemented to the rubber body and preferably being to someextent inserted in such body, as indicated at 4. Inserted and preferablyscrew threaded in the outer portion of the tube 3 is a valve carrier 5having an annular flange 6 between which and the tube end, a

gasket 1 is compressed. Set into the inner face of the carrier 5 is anannular valve seating annulus 8 formed preferably of rubber, suchannulus being engaged by a conical valve member 9 controlling a port Itformed axially of the carrier. Through said port projects a pin llrigidly carried by the valve member, such pin extending into a chamberl2 inwardly opening'in the carrier, and a spring l3 coiled in saidchamber bears outwardly on an abutment M on thepin to hold the valvemember normally firmly seated.

Carried and closed by the valve member 9 and elongated inwardlytherefrom is a cylindrical air chamber I5, formed preferably of rubberand expansible lengthwise. This expansibility derives from forming saidchamber in its end portion adjacent to the valve member with one or moreannular corrugations I6. It is preferred, as shown, to dispose the innerend portion of the valve member within and cement it to the outer end ofthe chamber [5. To admit air to the chamber 15 a passage I1 extends fromthe inner face of the valve member to the seating portion of its conicalface, whereby said passage is closed or opened according as the valvemember engages or disengages its seat. The chamber I5 is disposed withinand reinforced by a cylin-' drical jacket l8 having a closed inner end,said jacket being sufficiently spaced inwardly from the tube 3 toprovide for adequate air delivery to the tire. Said jacket may be formedof any suitable light sheet material such as metal or a plastic, lackingin material elasticity. It is preferred to cement or otherwise securethe entire non-corrugated peripheral portion of the container to thejacket and to similarly secure to each other the inner ends of thecontainer and jacket. It is further preferred to form the jacket with anoutward extension lBa beyond the chamber l5, such extension surroundingthe inner portion of the valve member when normal pressure prevails inthe tire. The extension l8a, or some other annular portion of the jacket[8 is exteriorly colored red, or some other conspicuous color, and thecoloring material is preferably luminous so that the indicator mayfunction in darkness. Such colored portion is concealed, when tirepressure is normal, by an opaque coating IQ of paint or other materialapplied to the tube 3. The flange 6 is threaded for engagement by theusual stem cap 20 which may seat against the gasket 1 to assure an airseal.

In use of the described indicator, equal pressures normally prevailwithin and around the jacketed chamber l5, such pressures being thatwhich the tire is designed to carry. Under such conditions the chamberi5 is collapsed, as in Fig. 1, being biased by its resiliency to thatposition. In such position, thereis complete concealment of the coloredwarning portion I811 of the jacket by the opaque coating l9 of the tube3. When pressure in the tire drops due to leakage .or any other cause,the balance of pressures is disturbed and there results an expansion ofthe chamber l5. The amount of expansion depends of course on pressuredepletion in the tire and further depends on the collapsedlength-soi thechamber j 5, That is tosay, the extent to jlvhich said chamber expandsresponsive to any ressure drop in the tire may (by Boyles law) beincreased or diminished by increasing or diminishing the length andhence the volume of saidichamb'e'r. Thus by preselecting a properlength, the chamber may be adapted to undergo a certairr'desiredexpansion for a predetermined;depletiorrs'ofitire vailing in the tire,and a signal element movable by said chamber upon its expansion due to adepletion .of the tire pressure.

2. In-a low. pressure tire signal, the combinationw'ith a tire valvestem having a transparent pressure. As the chamber expands, itshiftsfiiejacket 18 inwardly and registers the signal portion i811 of thejacket'either partially or fully with the window formed'by the'uncoatedportion oftheitubejt". Thus theldvic'e not only 'providesa visualindication of depleted pressure but further shows at least approximatelythe amount ofidepletioh: The jacket l8 performs an important function inreinforcing the chamber l5 and preventing material circumferentialexpansion thereof. Thus the 'elastio tension' of theiicon'fin'ed air ismade fully e'ifec'tivelengthwise of the valve stein and there is avoidedsuch wear and frictional resistance s would be imposed on the chamber l5wereit permitted by circumferential expansion to exert outward pressureon the tiibe 3. Fig, 4' discloses an J'indicatin'g unit'ctiinprising avalve member 9', expansible chamber l5, and ajac'ket l8, which'jinit isslightly modified from the'constructi'on first described. Thismodification consists merely in omitting the port I! of the valve memberwhereby 'air at a predeter mined pressure i's'p'ermanritly sealed withinthe expansible chamber; The. pressure employed would "of 'oourse'be thatbest suited to the tire in the Valve stem of which said unit, i'si'to"be installed. The modified unit will respond expansively to depletedtire pressure just as in the first'described construction.QItis'realized that various types of pressure 'indi'cato'rshave beendesigned for installation on the removable screw caps z'of ftire'valve'istems. These, however, are open to the objection .thatsuch caps may beeasily stolen or lost; The'c'onstriiction nowdescribed is preferablefurther'be'cause of its supe rior simplicity and of the thoroughprotection from damage. derived from its location within the valve stem.T v V An important merit, of the:construction shown inFig.4,whichpermanently seals a body of gas in the. exp'ansible chamber .at apressure for which the 'tir'eis designed, liesin the fact. thatthiindicating extension i8'a of the jacket progressively shiftsto ahidden position as a requi site pressure isb'uilt up by inflation. Thuswhen said extension becomes fully hidden, inflation may be discontinued,without need of consulting any gauge on the hose or applying a testgauge.

It'is'a distinctive and valuablefe'ature of. the disclose'dindic'ator,in either illustrated form, that balanced pressures are produced betweentwo volumes of air' ratherithan' between air and a spring;"Theindic'at'ions derived from a spring oppose to pressure'in a tire maysuifer a considerable loss'of accuracyfdue to temperature- T .p ortion,;oifia -movable signal element within said stem positioned to beobserved through said transparent portion in .at least one position ofsuch element, an expansible actuator for said signal element disposedwithin the stem; and

exercising an expansive effort, such effort being counterbalanced by thepressure of airfinth tire induced pressure variations of the air- Thiselement of error is eliminated when pressures of two volumes of air areopposed, since they respond alike to temperature variations.

What 1 claim is: h

A 1. 'In a low pressure 4 tion wane; tire valve stem and its valve, "ofan tire signal, the combinaand stem when such pressure is'norma'l,"andbeing adapted to overcome such pressurefwhen it is subnormal, and ananchorage provision for said actuator.

3. In a low pressure tire signal as setfo'rthin claim 2, a valve memberin said stem controlling and forming said delivery or 7 air to the tire,anchorage provision. a

4. In' a low piessuretire signal, the'combina tion with a tire valvestem, a eem resseaair chamber within saidfstehif expansible' and*exercising an expansive e'fiort toward the inner end of the stem; andopposed insuch effort by'the pressure oiia ir in the, tire and stemfmanssub st l fixing a Po on d,c iambs .v th respect to the stem, a valvecontrolling both the admission ofairto. thetire ah'dtos'aid air chambeen a d a s nal. lem nt b eby chamber 'in 1fts;expansion. H

5. In a low pressure tire signal; the combined.- tion with a tire valvestems-of a member within said stem having a port fordeliveryof air-tothe aid iair tire, a'valve member normally closing. sai'dport,

a compressed air chambercarriedbysaid valve member and expansible towardthe inner end of the stem but restrainediroih such expansion-by 7pressure in the tire and stem when such pressure 7 is normal, the valvememberhaving a passage iordelivering air to said air chamber, the inletof said passagebeing in the seating face-of'the valve member and henceclosed when the valve member is seated, and a signalelementactuable byexpansive travel of the air chamberi V a 6 In; a low pressure tiresignal, the combina+ tion with a tire valve stem having a tubulartransparent; portion, of -acylindrical element slidable within andlengthwise of' said stern for effecting exposure of a signalthrough saidtransparent portion, an expansible actuator forgsaid element within thestem-,exericising anexpansive efiort, such efiort being counterbalancedby the pressure of air inthe; tireand stem when such pressure is normaland overcoming such pressure when it is subnormal, and'meanssubstantially fixinga portion of said actuator with respect to the stem;

7. In a low pressure tire signal, the combinationwith a tubular valvestem having a transparent portion and an air passage extended throughsuch portion, of avalve member mounted inrand controlling air deliverythrough such passage, and a low pressure indicator operatively disposedwithin the stem including a signal ex posed through said transparentportion.

8.. A low pressure tire signal as setforth in claim '7, said signalbeing disposed between the tire and said valve member and in the air passage controlled by the valve member.

9. A low pressure tire signal as set forth in claim 7, said signal beingcylindrical and substantially coaxial with the stem.

10. In an indicator, the combination with a tire valve stem and a valveassembly inserted in the stem and comprising a member ported for airdelivery to the tire, a valve member seating on the ported member toresist air escape, and means yieldably urging the valve member to itsseat, of pressure indicating means fully carried by the valve memberwithin the stem, the stem having a transparent portion to expose saidmeans.

11. In a low pressure tire signal, the combination with a tubular valvestem having a flexible tire-engaging portion and a substantially rigidextension from said portion including a transparency, the joint betweensaid flexible portion and extension being impermeable to air, of a valvemember mounted in said extension and controlling air delivery throughthe stem, and a low pressure indicator operatively disposed within thestem including a signal exposed through said transparency.

12. In a low pressure tire signal, the combination with a pneumatic tireand a tubular stem communicating with and extending from the tire, of achamber within and elongated lengthwise of the stem, confining a gasunder a pressure substantially equal to that desired in the tire, meansfor anchoring one end of said chamber, the chamber being expansible towithdraw its other end from said anchoring means and being resisted insuch expansion by air in the stem at tire pressure, and a signal movablewithin the stem by expansion of said chamber, the stem being transparentfor at least a portion of its length to expose said signal.

13. In a low pressure tire signal as set forth in claim 12, said chamberhaving an inlet thereto, means for admitting air to said chamberresponsive to a material increase of air pressure in the stem over thatof the gas within the chamber.

14. A low pressure tire signal as set forth in claim 12, said signalbeing cylindrical and at least partially confining said chamber andresisting its lateral expansion.

15. A low pressure tire signal as set forth in claim 12, said chamberbeing expansible toward the tire-engaging end of the stem.

16. In a low pressure tire signal, the combination with a pneumatic tirehaving a provision for correcting pressure depletion, of a low pressuresignal, a chamber for confining air at the pressure desired in the tireexpansible to actuate said signal and opposed in its expansion by thepressure of air in the tire, means anchoring a portion of said chamber,and means for correcting any pressure depletion in said chamberresponsive to correction of pressure depletion in the tire.

17. In a low pressure tire signal, the combination with a pneumatictire, of a stem forming a passage for air delivery to said tire andhaving a transparent portion surrounding said passage, a movable signalwithin said passage positioned to be observed through said transparentportion in at least one position of such signal, and means for movingsaid signal responsive to a depletion of tire pressure. v

18. In a low pressure tire signal, the combination with a tire valvestem and its valve, of signal means including an expansible chambercarried by said valve and extending toward the inner end of the stem,said chamber confining a compressed gas and, when non-expanded,maintaining such gas at a pressure equal to that desired in the tire,said chamber being exteriorly subject to the pressure prevailing in thetire.

19. In a low pressure tire signal, the combination with a tire valvestem having a transparent portion, of movable signal means within saidstem, including a part positioned to be observed through saidtransparent portion in at least one position of such part, and includingan expansible member exercising an expansive eifort and normallycounterbalanced in such efiort by the pressure of air in the tire andstem, and adapted to overcome such pressure when it is subnormal, andmeans for substantially anchoring a portion of said expansible memberwith respect to the stem.

20. In a low pressure tire signal, the combination with a tire valvestem, of signal means including a compressed air chamber within saidstem expansible and exercising an expansive effort toward the inner endof the stem, and opposed in such effort by the pressure of air in thetire and stem, an anchorage provision for said chamber, and a valvecontrolling both the admission of air to the tire and to said airchamber.

21. In a low pressure tire signal, the combination with a tire valvestem, of a member within said stem having a port for delivery of air tothe tire, a valve member normally closing said port, and signal meansincluding a compressed air chamber carried by said valve member andexpansible toward the inner end of the stem but restrained fromexpansion by pressure in the tire and stem when such pressure is normal,the valve member having a passage for delivering air to said airchamber, the inlet of said passage being in the seating face of thevalve member and hence closed when the valve member is seated.

22. In a low pressure tire signal, the combination with a pneumatic tireand a tubular stem communicating with and extending from the tire, ofsignal means including an expansible chamber within and elongatedlengthwise of the stem and confining a gas under a pressuresubstantially equal to that desired in the tire, and an anchorageprovision for an end of said chamber, expansion of the chamber beingresisted by air in the stem at tire pressure, the stem being transparentfor at least a portion of its length to expose a part of said signalmeans.

HAROLD G. RENNER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 762,299 Fulton June 14, 19041,249,112 Keister Dec. 4, 1917 1,400,848 Anderson Dec. 20, 19211,539,030 Sweetland May 26, 1925 1,570,397 Preston Jan. 19, 19261,582,523 Larson Apr. 27, 1926 1,606,740 Badowski Nov. 16, 19261,755,163 Pulverman Apr. 15, 1930 1,807,752 Poster June 2, 19311,856,199 Tagle et a1. May 3, 1932 2,154,901 Hulse Apr. 18, 19392,225,674 West Dec. 24, 1940 2,229,192 Schultz Jan. 21, 1941

